1. Field of the Invention
The present invention relates to a resin-sealed semiconductor device in which a semiconductor chip is sealed with a resin.
2. Description of the Related Art
In a conventional automotive resin-sealed semiconductor device, a pair of silicon chips are integrally molded with a resin so as to minimize the size of the resin-sealed semiconductor device. A first chip carries a power transistor for driving an electric load, and the second chip has a control circuit for controlling the power transistor. When the power transistor is designed to control high power loads, the molding resin must have good thermal conductivity because the power transistor becomes hot. Moreover, when the size of the second silicon chip is large, the molding resin needs to have a low stress.
One conventional molding resin uses fused silica or crystal silica as a filler. However, such resin can not be mixed to have both good thermal conductivity and low stress at the same time. If the molding resin has a low thermal conductivity, the chip will overheat. If the resin has relatively high stress, the passivation film formed on the silicon chip will be easily cracked. In either case, the semiconductor devices will be susceptible to break down. Consequently, the reliability of the semiconductor device is significantly reduced.
Japanese unexamined Patent Publication No. 63-183915 and Japanese unexamined Patent Publication No. 62-240313 disclose a resin including aluminum oxide as a filler to increase the thermal conductivity of the resin. However, even such a resin does not sufficiently reduce the stress of the resin semiconductor device.